The present invention pertains to a dual component injector, especially for internal combustion engines, with a nozzle body that has a nozzle outlet, a valve needle for opening and closing the nozzle outlet, a first feed channel for supplying a first fluid to the nozzle outlet, a second feed channel for supplying a second fluid to the nozzle outlet, and, optionally, a fluid chamber which is located in the nozzle body and which is connected to the nozzle outlet.
Dual component injectors of this type are used, for example, during the start-up phase in internal combustion engines in order to inject into the combustion chamber a fuel that is different from the fuel used for normal operation. A low boiling fuel is usually injected for the start-up of the internal combustion engine, making it possible to comply with considerably more stringent exhaust emission standards than with a conventional injection process. A principal advantage of dual component injectors used in this way resides in the very small changes that have to be implemented in the internal combustion engine itself, together with the fact that the standard wiring and ignition of the internal combustion engine can be adopted in their entirety.
German publication DE 39 09 750 C2 describes a similar process in the form of a start-up aid for an internal combustion engine.
A dual component injector of this type is known from German publication DE 199 59 851 A1. In this case, a slide gate is arranged in one chamber of the nozzle body, and, depending on its position, this slide gate either connects the first feed channel or the second feed channel to the nozzle outlet.
One disadvantage of this injector resides in the fact that the start-up fuel and the fuel that is used for normal operation are capable of intermixing very readily. After the internal combustion engine has been switched off, and thus prior to the following start-up thereof, normal fuel is still located in the region of the nozzle outlet, which leads to this normal fuel being injected into the combustion chamber during the first injection process.
However, this runs counter to the actual basic idea behind these injectors, i.e. straight away at the start-up phase of the internal combustion engine to inject into the combustion chambers the start-up fuel that is intended for this purpose. Furthermore, this slide gate has proven to be unsuitable in practice, especially with regard to its sealing performance and its response characteristics.
One object of the present invention is therefore to create a dual component injector that ensures that, straight away during the first injection process, only the second fluid, which is specifically intended for this purpose, is released via the nozzle outlet. In addition, the dual component injector specified in the invention should have a simple structure and hence exhibit a high degree of reliability.
In accordance with the invention, the second feed channel is connected to the fluid chamber or to the first feed channel via at least two bored holes. The bored holes open out in the fluid chamber or the first feed channel in such a way that the second fluid produces a swirling flow pattern in the fluid chamber or in the first feed channel.
As a consequence of the drilled out holes in accordance with the invention, which connect the second feed channel to the fluid chamber or to the first feed chamber, and which are arranged in such a way that the second fluid produces a swirling flow pattern in the fluid chamber or in the first feed channel, the start-up fuel (when the dual component injector specified in the invention is used e.g. in an internal combustion engine) is capable (as a result of the swirling flow pattern that is being produced) of displacing normal fuel or, more generally, the first fluid, which may still be located in the fluid chamber or in the first feed channel, from the nozzle outlet without becoming intermixed with it. As a result, only the start-up fuel is located in the vicinity of the nozzle outlet and, during the first lifting off phase of the needle valve, only start-up fuel, or the second fluid, is released via the nozzle outlet.
In this manner, an extremely functional dual component injector is created at very low cost in terms of construction, especially since there is no movement of mechanical components in the interior of the injector, while this dual component injector, when used in internal combustion engines in particular, ensures the production of a very low quantity of injurious substances straight away during the start-up process, and consequently allows compliance with very low emission values.
Naturally, the dual component injector specified in the invention can also be used in other applications, e.g. in air conditioning units, humidifiers, and reformers of fuel cells.
Advantageous embodiments and further developments of the invention arise from the subsidiary claims as well as from the following example of an embodiment that is illustrated in principle by way of the drawings.